Rolling mill



March 29, 1965 H. H. HIRSCH ETAL 3,242,530

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United States Patent 3,242,530 ROLLING MILL Harold H. Hirsch and Richard A. Speer, both of Schenectady, N.Y., assignors to General Electric Company, a corporation of New York Filed May 29, 1964, Ser. No. 371,225 2 Claims. (Cl. 18-9) This invention relates to rolling mills and more particularly to rolling mills for use in compacting metal powders into a dense metal sheet.

When powder is fed to a rolling mill, whether operating vertically or horizontally, low density edges are produced and tearing or cracking is often encountered. Obviously, a product of such material is undesirable from the standpoint of the quality of the material produced and the ultimate cost of the final product. In the past, several methods for insuring proper densification of the powder metal at the sheet edges have been suggested but the high pressures necessary to the successful rolling of powder metals have caused problems that have never been fully solved.

It is a principal object of this invention to provide a new and improved metal powder compaction mill having edge control means confining the roll gap at the ends of the rolls which permits the rolling of sheet having edges free of cracks and related defects.

Another object of this invention is to provide a mill for rolling metal powder into compact sheet in which the edge control means are always and continuously retained entirely against the ends of the rolls.

Other objects and advantages of this invention will be in part obvious and in part explained by reference to the accompanying specification and drawings.

In the drawings:

FIG. 1 is a schematic end elevation showing a pair of compaction rolls mounted in cooperating relationship defining a roll gap in which metal powder is compacted and showing the relationship of the edge control strips of this invention;

FIG. 2 is a partially sectioned view taken along the line 22 of FIG. 1; and

FIG. 3 is a top plan view similar to FIG. 2 showing an alternative means for forcing the edge control strips against the ends of the roll.

Generally, the mill of this invention comprises a pair of rolls which are mounted in cooperating relationship to define a roll gap which can be formed by the separation of the rolls under load or initially set with a finite separation as shown in the three figures, where metal powder is compacted into dense, continuous sheet. The ends of the rolls, in the region of the gap, are closed by elongated metal strips which are of sufficient thickness to be free of warpage, camber, etc. These gap-sealing strips or edge control strips are, by appropriate means, forced tightly against the ends of the rolls in a manner such that maximum inward pressure is exerted against them in the region of the roll gap. While the mill is especially useful in conjunction with metal powders, it can have equal application in the rolling of sheet metal to reduce edge cracking and tearing.

The general construction and operation of the mill can be seen in FIG. 1 wherein numeral represents the pair of rolls mounted in cooperating relationship on journals 11. The rolls define a roll gap 12 where metal powder 13 from the hopper and feed tube 14 is compressed to its maximum density. It is at this location that there is the greatest tendency for the metal powder to be forced outwardly from the center toward the ends of the rolls and 3,242,530 Patented Mar. 29, 1966 thereby result in sheet, the density of which varies across its width. Since high pressures are required when metal powders are being rolled, it is necessary that the edge control means 20 be held tightly against the rolls in the area of the roll gap with considerable force.

FIG. 2 shows one way in which strip 20' can be maintained in tight cooperating and sealing relationship with respect to rolls 10 and the ends of the roll gap 12. The means used in this case is mounted directly on the roll journals and comprises a member constructed of a ringlike body 21 and a shoulder or collar 22. This member is secured tightly, by any appropriate means, to journal 11 so that it can hold strip 20 tightly against the ends of the rolls as shown in the drawing. This construction is advantageous since any Wear occurring in strips 20 can be compensated for merely by moving the retaining members inwardly toward the ends of rolls 10 and again locking them to the journal.

The arrangement of FIG. 3 illustrates a modified form for urging strips 20 tightly against the rolls 10 to enclose the roll gap 12. Here again, the area of maximum exertion of pressure is in the region of the roll gap, the pressure coming from any suitable source, such as a hydraul-ic system, through the yoke 25 and roller 26.

One advantage which the present system provides is that of minimizing sliding contact between the inner surface speed as the surface of the rolls or the compacted sheet. Since the strips are elongated in form, the movement of the strips is essentially parallel to the movement of the compacted powder until well beyond the region of maximum compaction and it moves at approximately the same speed as the surface of the rolls or the compacted sheet. This provision which can be obtained by either using elongated straight strips or a strip in the form of a large closed ring, reduces the possibility of breaking or otherwise damaging the edges of the compacted powder. FIG. 1 of the drawings illustrates how the feed would occur with the strips in the form of a large closed ring.

One additional factor which is important in effecting adequate sealing is that of ensuring that lateral movement of the strips 20 is essentially precluded so that no forces are introduced which would tend to break the edges of the compacted sheet. In the present arrangement, it has been found that if the strips 20 are made of a width essentially equal to the distance between the roll journals that lateral movement of the strips is precluded and the strip will feed uniformly and smoothly past the roll gap without causing any damage to the edges of the strip.

It is also possible to laterally spread the strips 20 once they are past the minimum roll gap to free the compacted sheet which will Want to expand laterally. The lateral spreading can be accomplished by flexing the strips outwardly through the use of fingers, clips or even magnetically without destroying the closure at roll gap 12.

Although the present invention has been described in connection with preferred embodiments, it is to be understood that modifications and 'variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and the appended claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A rolling mill for compacting metal powder into sheet metal comprising, a pair of rolls mounted in cooperating relationship defining a roll gap in which the metal powder is compacted, moveable metal strips of substantially greater length than width positioned in contact with 3,242,530 3 4 the ends of said pair of rolls to close the roll gap and to References Cited by the Examiner move past the gap with the metal powder during compac- UNITED STATES PATENTS tion thereof into sheet metal, and means mounted in operative relationship with said strips retaining them in 25346 3/1963 Heck. 18 9 contact against the ends of the rolls in the region of the 5 4/1960 Melvlue et 1819 Ion 2,965,926 12/1960 Von Haase 189 XR 2. A rolling mill as defined in claim 1 wherein the 3,010,148 11/ 1961 Dash width of the elongated metal strips is substantially equal to the distance between the 1,011 journals. WILLIAM J. STEPHENSON, Primary Examzner. 

1. A ROLLING MILL FOR COMPACTING METAL POWDER INTO SHEET METAL COMPRISING, A PAIR OF ROLLS MOUNTED IN COOPERATING RELATIONSHIP DEFINING A ROLL GAP IN WHICH THE METAL POWDER IS COMPACTED, MOVEABLE METAL STRIPS OF SUBSTANTIALLY GREATER LENGTH THAN WIDTH POSITIONED IN CONTACT WITH THE ENDS OF SAID PAIR OF ROLLS TO CLOSE THE ROLL GAP AND TO MOVE PAST THE GAP WITH THE METAL POWDER DURING COMPACTION THEREOF INTO SHEET METAL, AND MEANS MOUNTED IN OPERATIVE RELATIONSHIP WITH SAID STRIPS RETAINING THEM IN CONTACT AGAINST THE ENDS OF THE ROLLS IN THE REGION OF THE ROLL GAP. 